Australia plane had 'right' to watch China navy vessel in its waters - PM Morrison

The P-8A Poseidon - a maritime patrol aircraft - detected a laser emanating from a People's Liberation Army Navy (PLAN) vessel last Thursday, and Australia released photographs of two Chinese vessels sailing close to its north coast.

Australia's department of defence said on Tuesday that the aircraft dropped sonobuoys after the lasing incident, and that the surveillance devices aren't a shipping hazard.

"Our surveillance planes have every right to be in our exclusive economic zone and keeping a close eye on what people are up to," Morrison told reporters on Tuesday.

"The fact they were put under threat is extremely disappointing," he added.

The Chinese guided missile destroyer and an amphibious transport dock were sailing east through the Arafura Sea between New Guinea and Australia, and later passed through the narrow Torres Strait, Australia's defence department says.

Beijing says the Chinese ships had a legal right to be in international waters, which Australia has not disputed.

China's defence ministry on Monday said the surveillance plane had dropped a sonobuoy, which can help detect submarines, near the Chinese ships, and had flown as close as 4km (2.5 miles) from the convoy, which it said was "provocative and dangerous".

Australia's department of defence on Tuesday said that the aircraft had acted in a safe manner and that the use of sonobuoys for maritime surveillance is common practice.

"No sonobuoys were used prior to the PLA-N vessel directing its laser at the P-8A aircraft on 17 February. Some sonobuoys were used after the incident but were dropped in the water a significant distance ahead of the PLA-N vessel," it said.

The devices "collect passive acoustic data" on ships and submarines, it said.

The aircraft was 7.7km from the Chinese naval vessel at the time of the lasing incident, it said, and the closest it flew was 3.9km, which Australia said was standard for a visual inspection of a vessel.

"Australia expects all foreign vessels entering its maritime zones to abide by international law, particularly the UNCLOS," the statement said, referring to the United Nations Convention of the Laws of the Sea.

On Tuesday, Morrison announced separately Australia would spend A$804 million ($578 million) to buy drones and helicopters and set up mobile stations in Antarctica, because Australia needed to "keep watch" on the region.

He said that China did not share Australia's objectives in Antarctica, 42% of which is claimed by Australia, and that Beijing wanted to exploit its resources.